Method for reducing hydrogen absorption during chemical milling

Abstract

The invention provides method and apparatus for chemical milling of a metal part in a milling solution that reduces hydrogen absorption by the part wherein, the metal part to be milled, which serves as the anode, and a cathode of more noble metal than the anode, are mounted in such solution. Unlike the prior art, the cathode and anode are separated in such solution but electrically connected by a conductor therebetween, which conductor is insulated from the milling solution. Thus anode and cathode are mounted, spaced apart in the milling solution, so that metal dissolves from the anode surface, milling such part while electrons flow from anode to cathode by said conductor so that hydrogen forms at the cathode, removed from the anode part, to reduce hydrogen absorption by such part. The anode part can be of, eg. titanium and the cathode of a more noble metal, eg. platinum, which serves to draw the hydrogen to the cathode and away from the anode part, preventing or reducing absorption of hydrogen into, eg. the titanium part and consequent hydrogen embrittlement thereof, which occurs in the prior art.

What is claimed is: 
     
       1. A method for chemical milling of a metal part in a milling solution that reduces hydrogen absorption by said part comprising, a) selecting said metal part from the group consisting of titanium and titanium alloy and having said metal part serve as an anode,   b) providing a cathode of a more noble metal than said anode,   c) connecting said anode and said cathode by an electric conductor that is insulated from the milling solution,   d) placing said cathode in said solution and   e) placing said anode in said solution but at a distance from said cathode such that metal dissolves from the anode surface into solution and the electrons flow from anode to cathode through said conductor and hydrogen forms at said cathode, removed from said anode, to reduce hydrogen absorption by said metal part.   
     
     
       2. The method of claim 1 wherein said anode part is of a metal selected from the group consisting of titanium and titanium alloy and the cathode is a metal selected from the group consisting of platinum, palladium, rhodium, iridium and gold. 
     
     
       3. The method of claim 1 wherein said anode is placed in said solution between a plurality of spaced cathodes. 
     
     
       4. The method of claim 1 wherein said solution is an acidic conductive aqueous solution.